Fix stats summary/exit code when logging is disabled (#657)

Disabling logging would cause both the stats at the end, but more
crucially, the exit code (if errors occurred), to be incorrect.

Resolves: #652

src/cargo-deny/check.rs

@@ -540,30 +540,28 @@ fn print_diagnostics(
 ) {
     use cargo_deny::diag::Check;
 
-    match crate::common::DiagPrinter::new(log_ctx, krates, feature_depth) {
-        Some(printer) => {
-            for pack in rx {
-                let check_stats = match pack.check {
-                    Check::Advisories => stats.advisories.as_mut().unwrap(),
-                    Check::Bans => stats.bans.as_mut().unwrap(),
-                    Check::Licenses => stats.licenses.as_mut().unwrap(),
-                    Check::Sources => stats.sources.as_mut().unwrap(),
-                };
-
-                for diag in pack.iter() {
-                    match diag.diag.severity {
-                        Severity::Error => check_stats.errors += 1,
-                        Severity::Warning => check_stats.warnings += 1,
-                        Severity::Note => check_stats.notes += 1,
-                        Severity::Help => check_stats.helps += 1,
-                        Severity::Bug => {}
-                    }
-                }
-
-                let mut lock = printer.lock();
-                lock.print_krate_pack(pack, &files);
+    let dp = crate::common::DiagPrinter::new(log_ctx, krates, feature_depth);
+
+    for pack in rx {
+        let check_stats = match pack.check {
+            Check::Advisories => stats.advisories.as_mut().unwrap(),
+            Check::Bans => stats.bans.as_mut().unwrap(),
+            Check::Licenses => stats.licenses.as_mut().unwrap(),
+            Check::Sources => stats.sources.as_mut().unwrap(),
+        };
+
+        for diag in pack.iter() {
+            match diag.diag.severity {
+                Severity::Error => check_stats.errors += 1,
+                Severity::Warning => check_stats.warnings += 1,
+                Severity::Note => check_stats.notes += 1,
+                Severity::Help => check_stats.helps += 1,
+                Severity::Bug => {}
             }
         }
-        None => while rx.recv().is_ok() {},
+
+        if let Some(mut lock) = dp.as_ref().map(|dp| dp.lock()) {
+            lock.print_krate_pack(pack, &files);
+        }
     }
 }